JPH11270636A - Parallel axes-reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize the load distribution of each pinion gear engaging with a final stage gear (output shaft gear) incorporated in the output shaft of a parallel axes-reduction gear. SOLUTION: A first gear 106 and a second gear 108 are incorporated in an input shaft 102, and both the gears are made up of helical gears so that their helix angles are in opposite directions. The input shaft 102 can be axially slid, and the axial position of the input shaft 102 is determined by a balance between an axial component (moving force) F1 generated due to torque t1 transmitted to the first gear 106 side and an axial component (moving force) F2 generated due to torque t2 transmitted to the second gear 108 side and is stabilized in state where both the components become equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel shaft gear reducer configured to distribute rotational torque of an input shaft to two systems, and to merge and transmit the distributed rotational torque to an output shaft simultaneously.

[0002]

2. Description of the Related Art Conventionally, in a parallel shaft gear reducer in which an input shaft and an output shaft are incorporated in parallel, various proposals have been made for a method and a device for transmitting a rotational torque from an input shaft to an output shaft.

FIGS. 5 (a) and 5 (b) show conventionally known parallel shaft gear reducers R1 and R2.

First, FIG. 5A will be described.

[0005] The parallel shaft gear reducer R1 has an input shaft 2 receiving rotation from a motor (not shown), and an output shaft (fourth shaft) 4 that outputs finally reduced rotation.

In this parallel shaft gear reducer R1, when a rotation torque is input to the input shaft 2, the rotation is first transmitted to the second gear 10 meshing with the first gear 20, and further the second gear 10 A fourth gear 14 meshing with the third gear 12 via a third gear 12 on a gear shaft (second shaft) 6 in which
Is transmitted to After that, the power is transmitted from the fifth gear 16 of the same gear shaft (third shaft) 8 as the fourth gear 14 to the sixth gear 22 meshing therewith, and finally transmitted to the output shaft 4.

The parallel shaft gear reducer R shown in FIG.
2 has a hollow shaft 5 as an output shaft, but its basic structure is almost the same as that of FIG.

In the parallel shaft gear reducers R1 and R2, 1
Since one gear meshes with one gear, particularly when it is desired to transmit a large rotating torque (high load), each shaft is made thicker and each gear (the first to sixth gears) ) Needs to be increased. However, it is often used especially in places where the installation space is limited according to the needs of consumers, and in this case, it is difficult to enlarge each shaft and each gear. In other words, when small size and high performance are desired, it is necessary to reduce the axial center distance between the input shaft 2 and the output shaft 4 (5) and to withstand a high load.

Therefore, a planetary gear having a speed reducer as shown in FIG. 6 is a typical speed reducer which causes a plurality of gears to mesh with one gear and distributes the rotational torque to transmit it to an output shaft. A gear reducer R3 is known. The planetary gear reducer R3 has a plurality of planetary gears 26 around the sun pinion 24, and can relatively easily increase the rotational torque (load) transmission capacity.

[0010]

However, in a planetary gear reducer R3 having a reduction section as shown in FIG. 6, as is well known, an input shaft and an output shaft (not shown) are concentric.
When it is desired to transmit the rotational torque from the input shaft to the output shaft having a different height, a separate parallel shaft reduction unit is required, resulting in a complicated structure and increased cost.

[0011] For this reason, a configuration in which the rotational torque of the input shaft is received by, for example, two gear pairs and distributed to separate systems (first shaft and second shaft), respectively, and the merged and transmitted to the output shaft is used in parallel. A method that can be achieved by the shaft gear reducer itself is conceivable.

That is, the first shaft and the second gear of the second gear are connected to the input shaft.
On the other hand, two gears, a first shaft and a second shaft, are provided in parallel with the input shaft, and the third and fourth gears are built therein, and mesh with the first and second gears, respectively. As a result, the rotational torque that has entered the input shaft is reduced from the first gear to the third gear.
Gear (first shaft) system, second gear → fourth gear (second gear)
Axis). The rotational torque distributed to the first shaft and the second shaft is caused by the engagement of the fifth and sixth gears incorporated on the first shaft and the second shaft with the output shaft gear incorporated on the output shaft. At the same time on the output shaft.

However, when the speed reduction structure having such a configuration is employed, the gears are distributed to the respective systems, particularly if the fifth and sixth gears have slightly different engagement strengths with the output shaft gear due to a mounting error or the like. When the rotational torque itself (load distribution) itself is not even, and in extreme cases, power is transmitted to only one side of the system, and the other side of the system simply rotates within the backlash range of each gear. Sometimes it becomes.

As described above, if the transmission torque from each gear to the output shaft gear (hereinafter referred to as the meshing strength) is different, naturally only the load on the gear most strongly meshed with the output shaft gear is increased. As a result, not only the wear on the gears increases, but also the allowable transmission capacity of the entire reduction gear cannot be attained the original capacity (two systems).

The gears are meshed in a complicated manner.
In fact, since it is rotating at a high speed and a high load, it is actually difficult to eliminate the non-uniformity of the load distribution, in combination with the difficulty in detecting the strength of the engagement itself. That was the actual situation.

Also, even if the rigidity of each gear and shaft is secured, machining accuracy and assembly accuracy are improved,
Even if the non-uniformity of the load distribution is eliminated to some extent by assembly adjustment or the like, the non-uniformity often occurs again with the passage of time.

The present invention has been made in view of such conventional problems, and is basically based on a parallel shaft gear reducer having a simple structure, and is capable of transmitting the rotational torque of an input shaft to a plurality of systems. Transmission capacity (load distribution) in each system while adopting a configuration that distributes and transmits, and finally joins and transmits to the output shaft
Automatically, and each gear of each system transmits power evenly, thereby ensuring high transmission capacity of the entire reduction gear without forming an overload state on only some of the gears. It is an object of the present invention to provide a parallel shaft gear reducer that can perform the operation.

[0018]

According to the present invention, there is provided an input shaft, an output shaft incorporated in parallel with the input shaft, a first gear and a second gear having the input shaft as a gear shaft; A gear shaft of a third gear meshing with the gear, a first shaft parallel to the input shaft; and a second gear shaft of a fourth gear meshing with the second gear, the second shaft being parallel to the input shaft. A shaft;
A parallel shaft gear reducer configured to simultaneously transmit rotations of a shaft and the second shaft to the output shaft;
A helical gear is used as the gear, and the input shaft is
The first gear and the second gear are assembled with the helical direction of the helical being reversed, and the third gear and the fourth gear are respectively connected to the first gear.
The gears and the second gear are incorporated into respective gear shafts so as to mesh with each other, and the relative positions of the first gear and the third gear in the axial direction, or the relative positions of the second gear and the fourth gear in the axial direction. The object has been achieved by making at least one of the positions displaceable.

According to the present invention, as a specific gear structure for simultaneously transmitting the rotations of the first shaft and the second shaft to the output shaft, this may be constituted by a spur gear. You may comprise a helical gear.

As will be described later, the third gear and the fourth gear
If at least one of the gears is slidable in the axial direction, it is possible to prevent an excessive thrust force from being applied to only some of the bearings.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view schematically showing a meshing structure of a parallel shaft gear reducer according to the present invention. FIG. 2 shows FIG.
FIG. 2 is a view as viewed from the right side of the paper in the direction of arrow II. FIG. 3 is a perspective view of the helical gear in section III of FIG. 1 as viewed from the right front side of the drawing of FIG.

First, a first embodiment of the present invention will be described with reference to FIG.

This parallel shaft gear reducer has an input shaft 102
And an output shaft 104 incorporated in parallel with the input shaft 102
A first gear 106 and a second gear 108 having the input shaft 102 as a gear shaft; and a third gear 1 meshing with the first gear 106.
14, a first shaft 1 parallel to the input shaft 102
10 and a second shaft 112 which is the gear shaft of the fourth gear 118 that meshes with the second gear 108 and is parallel to the input shaft 102.

The first shaft 110 and the second shaft 112 include:
A fifth gear 116 and a sixth gear 120 are respectively incorporated. The output shaft 104 has a fifth gear 116 and a sixth gear 116.
A seventh gear (output shaft gear) 122 that meshes with the gear 120 (which is the last stage gear) is incorporated.

That is, in the parallel shaft gear reducer, the rotational torque input to the input shaft 102 is changed to the first gear 106 →
Third gear 114 → first shaft 110 → first of fifth gear 116
The system L1 and the second gear 108 → the fourth gear 118 → the second shaft 112 → the second system L2 of the sixth gear 120 are distributed and transmitted to the fifth system 116 and the second system L2 of the first system L1.
The sixth gear 120 meshes with the (one) output shaft gear 122 at different positions P1 and P2 so that the rotational torque distributed and transmitted is merged and transmitted to the output shaft 104. I have.

In the first embodiment, helical gears are used for the first to seventh gears, and the first gear 106 and the second gear
The gears 108 are incorporated such that the directions of the twists are opposite to each other when viewed from a plane. That is, the direction of the torsion of the helical gear of the set of the first gear 106 and the third gear 114 and the direction of the torsion of the helical gear of the set of the second gear 108 and the fourth gear 118 with respect to the input shaft 102. Are set to be opposite to each other when viewed from a plane. The helical torsion angles θ of the first gear 106 and the second gear 108 are set to be the same.

The input shaft 102, the output shaft 104, the first shaft 110, and the second shaft 112 are each supported by bearings (not shown) so as to be rotatable. Other than 102, the input shaft 102 cannot slide in the axial direction, and only the input shaft 102 can slide in the axial direction. The structure that allows the input shaft 102 to slide in the axial direction is not particularly limited, and a known bearing structure can be appropriately employed.

As shown in FIG. 1 and FIG.
The gear 116 and the sixth gear 120 are a seventh gear (output shaft gear).
Since they are engaged at the same time as 122, they naturally have the same twisting direction.

Next, the operation of the first embodiment will be described.

When the torque at which the fifth gear 116 and the seventh gear 122 mesh is T1 and the torque at which the sixth gear 120 and the seventh gear 122 mesh is T2, the total torque received by the seventh gear 122 is T. Then, the following equation is established.

T = T1 + T2 (1)

Here, T1 corresponds to the torque transmitted to the seventh gear 122 via the first system L1, and T2 is the second torque.
This corresponds to the torque transmitted to the seventh gear 122 via the system L2. Needless to say, each system L1, L
Ideally, the rotational torque from the input shaft 102 is distributed to each of the two. However, as described above, if there is a machining error or an assembly error of the gear, the rotational torque is not necessarily equal to each other (equally). Is not realized, and only one becomes large. In this case, since the total torque T received by the seventh gear 122 is invariable, the other one ends up in an overload state as one of them decreases.

When the torque transmitted from the input shaft 102 to the first gear 106 is t 1, the torque transmitted to the second gear 108 is t 2, and the total is t, the following equation is naturally satisfied.

T / t = constant (2) T1 / t1 = T2 / t2 = constant (3)

Here, suppose that the transmission torque of the first system L1 becomes larger due to the variation of the meshing strength.
Assume that 1> T2. In this case, naturally, the relationship of t1> t2 is established by the above relationships.

On the other hand, when the power is transmitted by the meshing of the helical gear, the helical gear has a torsion angle (inclination) θ,
An axial component force proportional to the transmitted torque is generated at the mesh point. In the case of the first embodiment, in the first system L1, the output shaft 104 and the first shaft 110 are fixed in the axial direction, so that the input shaft 102 reacts in the direction indicated by the arrow in FIG. X receives a moving force F1.

Similarly, the input shaft 102 receives the reaction of the axial component generated at the time of power transmission between the input shaft 102 and the second gear 108, and the input shaft 102 moves in the direction of arrow Y in FIG.
Receive 2. Since the helical torsion angle θ is set to be the same for the first gear 106 and the second gear 108, the moving force F1 is proportional to the transmission torque t1, and the moving force F2 is proportional to the transmission torque t2. Therefore, if t1> t2 now, F
1> F2, and the input shaft 102 moves (slides) in the direction of arrow X by the moving force F1.

When the input shaft 102 moves in the direction of the arrow X of the moving force F1, the third gear 114 is fixed in the axial direction, so that the engagement between the first gear 106 and the third gear 114 (strength). ) Will be relaxed accordingly. When the engagement is loosened, the torque t1 transmitted there is naturally weakened. Conversely, on the second system L2 side, the input shaft 102 moves in the direction of the arrow X with the moving force F1 to increase the engagement between the second gear 108 and the fourth gear 118, and the transmission torque t2 here is reduced. Increase. That is, as a result, the moving force F
When 1 is weakened, the moving force F2 is relatively increased, so that the input shaft 102 is at a position where the moving forces F1 and F2 are exactly equal, that is, a position where t1 and t2 are equal (T1 and T2 are equal. Position).

When the transmission force t2 on the side of the second system L2 is larger, F2> F1, so that the operation described above is completely symmetrical with the operation described above, and F1 = F2.
It converges to the position where (t1 = t2, T1 = T2).

Thus, the fifth gear 116 and the sixth gear 116
One of the gears 120 is the seventh gear (output shaft gear) 1
22, the transmission torque T1 or T2
Is larger than T2 or T1, on the other hand, the input shaft 102 slides, and finally slides to a position where T1 = T2, and becomes stable.

The fifth gear 116 and the sixth gear 120
With respect to the so-called hunting phenomenon in which the meshing force becomes stronger or weaker in the meshing with the seventh gear 122, friction always exists at the time of meshing between the gear and the gear. By properly setting the slide resistance with respect to the total transmission force, it is possible to keep the slide resistance within a range without any trouble.

As a result, the first system L1 and the second system L2
Is the resulting transmission torque t1, t2 or T1, T2
Are distributed evenly, the load on the gears of each system L1 and L2 is evenly distributed, the durability of the gears can be improved, and the power loss and noise due to friction are minimized. It can be suppressed.

In the first embodiment, all the gears are constituted by helical gears. However, the fifth to seventh gears do not need to be helical gears. Similar effects can be obtained.

Next, a second embodiment of the present invention will be described.

The second embodiment has basically the same configuration as the first embodiment (all gears are helical gears). However, in order to reduce the load on the bearing of the third gear, the first embodiment This is an improved shaft structure.

That is, when all the gears are constituted by helical gears, in the first system, due to the direction of the helical gear,
The first gear is engaged with the fifth gear 116 and the seventh gear 122 to
The axial component force F3 generated on the shaft 110 and the first gear 10
6 and the third gear 114, the direction of the axial component force F4 (having the same magnitude and opposite direction as F1) generated on the first shaft 110 becomes the same. 200 has a very large thrust direction load.

Therefore, as shown in FIG. 4, a bearing 206 is sandwiched between a step portion 212 of the first shaft 210 and a plate 202 fixed to the first shaft 210 by bolts 204, and the bearing 206 is connected to the step portion on the housing side. The fifth gear 116 and the seventh gear 122
The axial component force F3 generated on the first shaft 210 due to the meshing with the shaft 200 is not applied to the bearing 200.

That is, the third gear 114 is connected to the spline 216
, And only the axial component force F4 generated by the engagement of the third gear 114 and the first gear 106 is applied to the third gear 114, Only the component force F4 needs to be received by the bearing 200. As a result, in the first embodiment (since no countermeasures were taken), the axial component force F3 generated by the engagement of the fifth gear 116 and the seventh gear 122 in the bearing on the third gear side, Gear 106 and third gear 114
Although both the axial component force F4 generated by the meshing with the above are applied, only the latter F4 is applied, so that the load is reduced accordingly.

On the side of the second system L 2, the direction of the thrust load applied from the fourth gear 118 and the direction of the thrust load applied from the sixth gear 120 are reversed depending on the direction of the torsion of the helical gear. A large thrust load does not occur in a specific bearing. Therefore, the second system L2 does not need to take any special measures as in the second embodiment, but does not specifically prohibit the same configuration.

[0051]

As described above, according to the present invention,
The rotation torque (meshing strength) from each gear meshing with the final stage gear (output shaft gear) incorporated in the output shaft can be automatically equalized, and can be applied to one specific gear. Without imposing a load, the transmission capacity inherent in each gear is fully exhibited, and as a result, downsizing and weight reduction can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a gear and shaft meshing structure of a parallel shaft gear reducer according to a first embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrow II in FIG.

FIG. 3 shows a seventh gear (output shaft gear) in the embodiment.
Perspective view showing a fifth gear and a sixth gear meshing therewith.

FIG. 4 is a cross-sectional view showing a support structure near a first shaft according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a conventionally known parallel shaft gear reducer.

FIG. 6 is a cross-sectional view showing a conventionally known planetary gear reducer.

[Explanation of symbols]

 102 input shaft 104 output shaft 106 first gear 108 second gear 114 third gear 118 fourth gear 116 fifth gear 120 sixth gear 122 seventh gear (output shaft gear) 110 First axis 112 ... Second axis

Claims (4)

[Claims] 1. An input shaft, an output shaft incorporated parallel to the input shaft, a first gear and a second gear having the input shaft as a gear shaft, and a third gear meshing with the first gear. A first shaft parallel to the input shaft, a gear shaft of a fourth gear meshing with the second gear, and a second shaft parallel to the input shaft; In a parallel shaft gear reducer configured to simultaneously transmit rotations of one shaft and the second shaft to the output shaft, a helical gear is used for the first to fourth gears, and the input shaft is The first gear and the second gear are assembled with the helical torsion directions reversed, and the third gear and the fourth gear are
The gears are assembled to the respective gear shafts so as to mesh with the first gear and the second gear, respectively, and the relative positions in the axial direction of the first gear and the third gear, or the second gear and the fourth gear Wherein at least one of the relative positions in the axial direction is displaceable. 2. The output shaft according to claim 1, wherein said first and second shafts are engaged with said output shaft as gears for simultaneously transmitting rotations of said first and second shafts to an output shaft. A parallel shaft gear reducer characterized by using a spur gear. 3. A gear structure according to claim 1, wherein said first and second shafts are incorporated into said first and second shafts, respectively, as gears for simultaneously transmitting rotations of said first and second shafts to an output shaft. A parallel shaft gear reducer characterized by using meshed helical gears. 4. The third gear and the fourth gear according to claim 3,
A parallel shaft gear reducer, wherein at least one of the gears is slidable on a first shaft or a second shaft.